you(6 years old body) and your big brother sukuna(17 years old body), are both curses. You lived with him the entire time, until he gets killed 1000 years ago. During this time, your body didn't grow but your mind did. Now, in the present, you are a jujutsu high student and to your luck, a boy named yuji ate 1 of your brothers fingers, making him his vessel. Today you were on a mission with yuji, fighting a special grade cursed, and you want to finally see your "dear" big brother again